1. Field of the Invention
The present invention relates to an apparatus for adjusting the origins of module heads of a surface mounting apparatus and method therefor, and more particularly to an apparatus for adjusting the origins of module heads of a surface mounting apparatus to which a dual gantry is applied and method therefor.
2. Description of the Conventional Art
A surface mounting apparatus SMA is used to perform the precise and high speed mounting of electronic components suitable for surface mounting the electronic components on a printed circuit board PCB. To this end, the SMA generally comprises an X-Y gantry, a module head, a vision unit and a transfer unit.
To move a module head in X-Y axes directions, the X-Y gantry is provided with a vision unit which is installed in vicinity of the module head. The vision unit is used to sense whether or not the electronic component taken by the module head are in accurate position and posture. Simultaneously with the taking of the electronic component by the module head, the PCB to be used for mounting the component is supplied by the transfer unit. When the PCB is transferred to a work site by the transfer unit, the module head performs the mounting of the electronic component.
The structure of the SMA for mounting the surface-mounting electronic components onto the PCB will be in detail described with reference to the drawing.
FIG. 1 is a front view of a conventional surface mounting apparatus. As shown in FIG. 1, the X-Y gantry 2 is provided on a top surface of a base frame 1. A module head 3 is assembled into the X-Y gantry 2, and the transfer unit 5 for supplying the PCB is installed between the base frame 1 and the module head 3. When the PCB is transferred to the work site by the transfer unit 5, the module head 3 takes the surface-mounting electronic component, is moved on the plane in X- and Y-axes directions to surface mount the component.
For a high speed mounting of the component onto the PCB, the module head 3 consists of a plurality of heads 3a, 3b, 3c. The heads 3a, 3b, 3c are arranged with a predetermined interval. Each head takes and mounts the component, whereby high speed mounting of the components is accomplished. High speed mounting of the components can be achieved by the module head 3 having a plurality of heads 3a, 3b, 3c, and the mounting precision is increased through the use of the vision unit 4 used for sensing the position and posture of the component mounted onto the PCB.
The vision unit 4 has a camera 4a for sensing the position and posture of the component taken by the module head 3 and analyses information on the position and posture sensed by the camera 4a. By such a analysis, the module head 3 can accurately mount the component on the PCB, and therefore the mounting precision is maintained.
The module head for mounting the component onto the PCB may need an adjustment of the origin thereof, which is necessary for performing the sensing of an accurate position to be mounted and the precise and high speed moving of the module head. A conventional method for adjusting the origin of the module head is conducted by a manual adjustment in which the operator manually moves the module head to the origin position marked on a bottom surface of the X-Y gantry in order to adjust the origin. In the case of such a manual operation, there occurs a problem in that the origin adjustment precision is reduced and unwanted accident may occur.
To improve the method for adjusting the origin based upon such a manual operation, a laser, reflection mirror, and an interferometer may be employed. The interferometer and the laser are installed in the module head, whereas the reflection mirror is installed in the fixed base frame. In operation, the laser radiates the laser light which is incident upon the reflection mirror which reflects the incident light. The phase difference of the reflected light is sensed by the interferometer, and used to obtain the distance between the currently fixed reflection mirror and the module head and then to measure the origin of the module head.
The measurement of the origin by using the interferometer requires a number of parts, i.e., the laser, the interferometer, and the reflection mirror. In the case of assembling such a plurality of parts into the SMA, there arises a problem in that the assembling procedures are complicated and the installation cost increases, etc.
Therefore, it is an object of the present invention to provide an apparatus for adjusting the origins of first and second module heads of a surface mounting apparatus to which an X-Y gantry is applied, by using first and second reference points, a mark indicating the origin, and vision units, and method therefor.
Another object of the present invention is to provide an apparatus capable of simultaneously adjusting the origins of the first and second module heads installed in the dual gantry, and method therefor.
Further another object of the present invention is to provide an improved precision of the origin adjustment in which the first and second reference points, the MIO and the vision units are used to adjust the origins of a plurality of the module heads, and the prompt adjustment by simultaneous adjustment of the origins.
Further another object of the present invention is to provide an easy incorporation of the origin adjustment apparatus into the surface mounting apparatus in that the first and second reference points, the MIO, and the vision units are used to adjust the origins of the first and second module heads.
According to one aspect of the present invention, there is provided an apparatus for adjusting the origins of module heads of a surface mounting apparatus for a dual gantry, the adjusting apparatus comprising: the X-Y gantry consisting of first and second X-axis linear motors and first and second Y-axis linear motors, and having X-Y plane on which first and second reference points and a mark indicating the origin (MIO) are set; first and second module heads installed at the first and second X-axis linear motors; first and second vision units installed in vicinity of the first and second module heads, respectively, and for sensing the first and second reference points and the MIO and generating and outputting coordinates of the sensed first and second reference points and the MIO; and a controller for driving the first and second X-axis linear motors and the first and second Y-axis linear motors to move the first and second vision units to the first and second reference points and the MIO, receiving the coordinates output from the first and second vision units to compute offset values relating to the first and second module heads, and, if there are the offset values, setting the origins of the first and second module heads by correcting the offset values.
According to another aspect to the present invention, there is also provided a method for adjusting the origins of module heads of a surface mounting apparatus for a dual gantry, the method comprising the steps of: moving first and second vision units to first and second reference points, respectively; after completing the movement, moving the first and second units to the MIOs and sensing the respective MIOs; while the first and second vision units sense the MIOs, checking whether or not a secure distance between the first and second vision units is ensured; with the secure distance between the first and second vision units being ensured, in case the sensing of the MIOs is completed, computing coordinates of the origins of the respective first and second module heads based on the distance traveled from the MIOs as a base point to the first and second reference points; after each of the coordinates of the origins of the first and second module heads is computed, computing offset values due to the differences of the distances traveled by the first and second module heads; and setting the origins of the first and second module heads by correcting the obtained offset values.